1. Field of the Invention
The subject invention relates to an assembly for cooling a power device.
2. Description of the Prior Art
Electronic semiconductor device technology continues to rapidly advance, producing devices that achieve heretofore unattainable operating speeds, packing density, and high-temperature compatibility. This last characteristic, high-temperature compatibility, is one of the more important features. High-temperature environments as well as high-power and high frequency applications are becoming increasingly important.
Many such high-power, high-temperature electronics applications inherently limit the ability to dissipate heat and power generated by the electronics. Thermal and power management as well as environmental protection of the electronics are therefore handled entirely by the electronics packaging. As a result, typical high-performance packaging criteria include mechanical strength, high thermal conductivity, close matching of device and package thermal expansion coefficients, low dielectric constant for accommodation of high frequency devices, and environmental protection, such as hermetic sealing.
In designing such packages, thermal management is important, especially at high power generation levels which increase the amount of heat created. Heat decreases the performance and operating life of the transistor. Moreover, heat generated at the collector-base junction can create a temperature buildup which may eventually cause the device to short-circuit. The power device may be mounted on a thermally conductive pad which acts as a heat sink and dissipates the heat generated by the power device.
Two examples of such a system are disclosed in U.S. Pat. No. 7,005,734 to Choi et al (the '734 patent) and U.S. Publication 2004/0173901 to Mallik et al (the Mallik publication).
The '734 patent discloses an assembly that includes a semiconductor die that extends radially from an axis and includes an upper surface and a lower surface. An upper substrate is disposed axially above the upper surface of the die to provide a first heat dissipation path from the die through the upper substrate. A lower substrate is disposed axially below the lower surface of the die for providing a second heat dissipation path from the die through the lower substrate.
The Mallik publication discloses an assembly that includes a semiconductor die that extends radially from an axis and includes an upper surface and a lower surface. An upper substrate is disposed axially above the upper surface of the die to provide a first heat dissipation path from the die through the upper substrate. A circuit board is spaced axially below the upper substrate to define a gap between the upper substrate and the circuit board. The circuit board defines a through hole having a periphery about the axis and includes a plurality of circuit board conductors. A plurality of first interconnectors are disposed in the gap and at the ends opposite one another of the upper substrate to create electrical conduction between at least one of the circuit board conductors of the circuit board and the upper substrate.
Although the prior art increases cooling capabilities, there is a continuing need for a simple, reliable apparatus to fabricate packages for electronic chips, so that the package provides high heat conductivity and dissipation, and high frequency response.